17. Chlorine: Too High Or Too Low, There Ain’t No In-Betweens

Chlorine is an element that causes some extreme reactions, and occasionally inspires some pretty extreme reactions in humans, too.

Featured above: An overly enthusiastic endorsement for dichlorodiphenyltrichloroethane.

Show Notes

A Quick Favor To Ask: If you’re enjoying the show so far, I would really appreciate if you would nominate The Episodic Table Of Elements for a Podcast Award. For instructions on how to do just that, and read more about why that would be such a huge favor for the show, check out the earlier blog post on the subject.

You Know Something John Snow: I found a particularly good short documentary about John Snow and the Broad Street pump on YouTube, and recommend giving it a watch if you’re not familiar with the story! Plus, that video thumbnail is just great.

Author Steven Johnson hosted a PBS miniseries a few years back called How We Got To Now, along with a companion book and several companion articles that can be found on the web. It was an excellent little series, quite reminiscent of James Burke’s Connections miniseries that aired back in the 70s. (Itself an incredible series and something of an inspiration behind this podcast.) In one of those articles, he explains how element 17 led to one of the most revolutionary fashions of all time:

Consider the early 20th-century scientific and public health breakthrough of adding calcium hypochlorite (or chlorine) to drinking water to kill bacteria. This innovation had a dramatic impact on mortality rates, but it also transformed our recreational habits. After World War I, ten thousand chlorinated public baths and pools opened across America; learning how to swim became a rite of passage. These new aquatic public spaces were the leading edge in challenges to the old rules of public decency during the period between the wars. Before the rise of municipal pools, women bathers generally dressed as though they were bundled up for a sleigh ride. By the mid-1920s, women began exposing their legs below the knee; one-piece suits with lower necklines emerged a few years later. Open-backed suits, followed by two-piece outfits, followed quickly in the 1930s. “In total, a woman’s thighs, hip line, shoulders, stomach, back and breast line all become publicly exposed between 1920 and 1940,” the historian Jeff Wiltse writes in his social history of swimming, Contested Waters.

The whole article is well worth reading in full, and the series is definitely worth watching if it’s airing on your local PBS station!

A Hard-Learned Lesson: In the 1990s, Greenpeace led an extremely ill-advised campaign based on dubious research indicating that chlorinated water may cause cancer. They managed to convince some important people in Peru, who stopped chlorinating their water supplies.

Predictably, horrible outbreaks of cholera soon followed. No cases of cancer are thought to have been prevented.

No one really needed any further proof that chlorination saves lives, nor that Greenpeace probably causes more harm than good in the world. But just in case, there you go.

Apologies To Limerick Originalists: I admit that I have made a minor edit to the limerick mnemonic about DDT. Every other version of the limerick includes as its fourth line, “para-dichloro,”  but no non-limerick source actually refers to DDT with the “para-” prefix. Thus, I took the liberty of altering the limerick. Pray I do not alter it any further.

Nothing Out Of The Ordinary Here: Just for illustration, one of those “mosquito fog” photographs I mentioned in the episode:

Image result for mosquito fog ddt children

DDT DisbelieversThis entire essay on Dorothy Colson’s fight against DDT is an incredible, admirable piece of scholarship well worth reading in its entirety. It’s a true testament to the value of documenting local history in such painstaking detail, even if it might not seem worthwhile for decades.

Click To Read Transcript


  1. Chapter XXXVII of this work by that pope says as much, if you care to translate it. Do a “Find in page” for “plumbum.”
  2. Periodic Table of Videos, Chlorine. 7:27.
  3. SafeDrinkingWater.com, John L. Leal — Hero Of Public Health. Michael J. McGuire, September 25, 2012. Ordinarily I wouldn’t source from a website like this, but it happens to be written by the same man who wrote The Chlorine Revolution, a  widely respected book on the subject.
  4. In Chancery of New Jersey, Between The Mayor And Aldermen Of Jersey City, Complainant, And The Jersey City Water Supply Company Et. Als, Defendants. p. 4,978.
  5. Water Quality & Health Council, Chlorination Of U.S. Drinking Water. May 1, 2008.
  6. Steven Johnson, How We Got To Now: Six Innovations That Made The Modern World. No page number given.
  7. The Citizen Machine: Governing By Television In 1950s America, p. 38-44. Anna McCarthy, 2013.
  8. Prometheans In The Lab: Chemistry And The Making Of The Modern World, p. 153. Sharon Bertsch McGrayne, 2001.
  9. Science History Institute, Beyond Silent Spring: An Alternate History Of DDT. Elena Conis, Winter 2017.
  10. Southern Spaces, DDT Disbelievers: Health And The New Economic Poisons In Georgia After World War II. Elena Conis, October 28, 2016.
  11. The New Yorker, Silent Spring — II. Rachel Carson, June 23, 1962.
  12. The New York Times, Rachel Carson, DDT And The Fight Against Malaria. Clyde Haberman, January 22, 2017.
  13. The New York Times, Rachel Carson Dies Of Cancer; ‘Silent Spring’ Author Was 56. Jonathan Norton Leonard, April 15, 1964.
  14. US Fish & Wildlife Service, Bald Eagle Fact Sheet.
  15. UNICEF, Malaria Fact Sheet.
  16. Journal Of Military And Veterans’ Health, DDT And Silent Spring: Fifty Years After. Cristobal S. Berry-Caban, Issue Volume 19 No. 4.
  17. National Geographic, Climate Change Pushing Tropical Diseases Toward Arctic. Craig Welch, June 14, 2017.

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